"Roy Lewallen" wrote:
Amateurs seldom communicate by surface wave, except for local contacts.
When the vertical is surrounded by real ground, attenuation of the sky
wave at lower angles occurs. One of the results of this is that the
antennas which concentrate energy more at lower angles end up losing a
greater fraction of the total radiated energy. This tends to decrease the
gain difference between a 5/8 and 1/4 wave vertical, for example, over a
typical sky wave path.
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I investigated your concept statements using NEC-2 models of 1/4-wave and
5/8-wave verticals in the 40m band (7.3MHz), working against the same
infinite ground plane of "Average" parameters.

* The 5/8-wave vertical has a peak gain of 0.2dBi,
16 degrees above the horizon.

* The 1/4-wave vertical has a peak gain of -6.4dBi,
26 degrees above the horizon, and its entire radiation
envelope is always within that of the 5/8-wave.

I don't know which range of elevation angles is considered most useful for
skywave paths on 40m, but it would appear that with equal tx power, a
5/8-wave vertical always will have a usefully better skywave than a 1/4-wave
vertical over a typical ground plane -- and probably by more than 3dB.

If you could check my conclusions on this I'd be grateful.

RF